Note

A graph of expected player interest over time.

Make players feel in control of their experience.

Functions that can pause and resume execution, similar to Python generators.

When tuning game values, double or halve them instead of nudging: it makes the effect obvious.

A game economy is meaningful when spending and earning money form a rewarding loop.

Complex interactions that arise naturally from a simple ruleset.

Strategic actions that aren't in the rules but arise naturally from playing the game.

On the power of unpredictable rewards.

Addictive games keep players exercising a skill, taking risks, and working a strategy simultaneously.

Plan to ship at half the budget, use the rest to make it great.